There is a need for weight reduction while maintaining high strength and high rigidity, in many fields such as automotive parts and electric devices. Accordingly, to use a resin as a portion of a member made of a metal, a metal member and a resin member are bonded to each other.
Heat welding is known as an example. In heat welding, a metal member is heated to the melting temperature of a resin or higher and, with the resin member being in contact with the surface of the metal member, the contact portion of the resin member is melted and bonded to the metal member.
Moreover, Patent Document 1 describes the following bonding: a bonding portion between a metal member and a resin member has a metal compound film and a molecular adhesive in order from the metal member side, and a portion in which the resin member is in contact with the molecular adhesive has a locally re-hardened portion formed by locally melting and then hardening the resin member.